Automatic pointing antennae system

ABSTRACT

A system and method for automatically positioning/directing satellite antennas towards a satellite with which it is to communicate. The system and method may use characteristics of symmetry of mutually exclusive orthogonal axes. By using the symmetry of the antenna main beams, the ideal direction of the antenna can be attained and, at the same time, maximum cross-polarization may be achieved. The cross polarization may be required in order not to interfere with the orthogonal polarization. The system and method may position the Antenna on three mutually exclusive orthogonal planes, including the azimuth plane, the elevation plane, and the polarization plane. The system and method may include an indoor unit, which may include a satellite receiver, a telemetric transmission, and supply of voltage to a control system and which may control a drive motor and/or an electronic search device; and an outdoor unit, which may include a supervisory unit, a motor, and a control unit. The outdoor unit is preferably configured to conduct a search in the three orthogonal planes which may facilitate positioning the Antenna with a high degree of accuracy.

[0001] This application claims priority to provisional U.S. ApplicationSer. No. 60/246,572 filed Nov. 8, 2000, herein incorporated byreference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to the field of satellitecommunications. More particularly, the present invention relates tosystems and methods for automatically setting-up antennas for very smallaperture satellite terminals.

[0003] Currently in the industry, to position an Antenna, a skilledtechnician is required to position the Antenna manually by use ofcertain positioning equipment. This equipment is separate from andexternal to the Antenna. This currently used manual mechanism requires aprofessional/skilled person to attend the location where an Antenna isto be installed and position the antenna, representing significantresources and costs. Further, this complex procedure is beyond thecapabilities of the average homeowner prohibiting the homeowner fromperforming a self installation. Hence there is a need for a low cost andsimple system and method which enables the average homeowner to installsatellite equipment.

SUMMARY OF THE INVENTION

[0004] In order to overcome the disadvantages of conventional systems,there are a number of objects and associated aspects of the presentinvention.

[0005] Aspects of the present invention include a mechanism forautomatically positioning/directing satellite antennas at an end userlocation towards a satellite with which it is to communicate. Withoutlimiting the foregoing, this mechanism can be used for antennas whichcomprise part of a satellite-based VSAT communications system forcommunication.

[0006] Other aspects of the invention include the automaticpositioning/directing of an Antenna without the need for a skilledperson to attend the Antenna installation site in order to position theAntenna. Further aspects of the invention include allowing aconsumer/end-user to direct/position an Antenna without any requirementfor input from a skilled technician. This represents significant costsavings and is especially significant for satellite-based VSATcommunications networks designed to be installed by a homeowner or inhome based applications.

[0007] Further aspects of the invention may include systems and methodswhich enable an Antenna to be automatically positioned/directed to apredetermined position. The systems and methods may include applying theuse of characteristics of symmetry of mutually exclusive orthogonalaxes. In these embodiments, by using the symmetry of the antenna mainbeams, the ideal direction of the antenna can be attained (this idealdirection is known as “maximum gain point”) and, at the same time,maximum cross-polarization may be achieved. The cross polarization maybe required in order not to interfere with the orthogonal polarization.

[0008] The positioning of an Antenna towards a satellite typicallyrequires a high degree of accuracy. In order for an unskilled person toattain this high degree of accuracy, the systems and methods containedherein may include:

[0009] 1. a maximum gain for receiving and transmitting satellitecommunications;

[0010] 2. a cross-polarization for the receiving frequencies andparticularly for transmitting frequencies. The cross-polarization may beadvantageous in that the system will not interfere with orthogonalpolarization; and

[0011] 3. maintaining symmetry of the receiving and the transmissionbeams, and particularly the main beam, for receiving and transmittingcommunication, so as not to interfere with satellite communication ofother satellites.

[0012] The above features may be utilized individually or incombination. Where used in combination, the above features have theadvantage of minimizing the positioning/direction error.

[0013] In aspects of the invention, the system and method may positionthe Antenna on three mutually exclusive orthogonal planes. Thesetypically include:

[0014] (i) the azimuth plane;

[0015] (ii) the elevation plane; and

[0016] (iii) the polarization plane.

[0017] In still further aspects of the invention, the system and methodmay include three sub-mechanisms each of which may contain instructionsfor mechanical and electronic positioning of the Antenna towards thesatellite. To do this with the degree of accuracy required for enablingsatellite communication, an accuracy greater than {fraction (1/10)}th ofthe beam width of the Antenna may be required.

[0018] In other aspects of the invention, the system and method maycomprises two principal components:

[0019] (a) an indoor unit (IDU), which may include a satellite receiver,a telemetric transmission (feed back on the strength of the signal), andsupply of voltage to a control system (which may be contained in theODU) and which may control a drive motor and/or an electronic searchdevice; and

[0020] (b) an outdoor unit (ODU), which may include a supervisory unit,a motor, and a control unit (e.g., an electronic control unit). Theoutdoor unit is preferably configured to conduct a search in the threeorthogonal planes which may facilitate positioning the Antenna with ahigh degree of accuracy. This is according to the messages received fromindoor unit telemetry.

[0021] By use of the symmetry principle of the receiving beam and thepolarization plane, a search may be conducted for the symmetry in eachone of the said planes. The symmetry principle may be applied to thesearch of the three dB points (−3 dB) for each one of the orthogonalplanes. By locating a signal from the satellite at a point of symmetry,it may be possible to find the point at which two points of symmetry areof the highest possible values. If we add further points of symmetry,such as the −5 dB point, it is possible to improve the positioningability of the systems and methods described herein and obtain a moreaccurate positioning of the main beam. As the number of symmetry pointsincreases, so does the accuracy of the systems and methods describedherein.

[0022] In still further aspects of the invention, the stages forimplementing the systems and methods described herein may include:

[0023] 1. a manual positioning of the Antenna in the three planesdescribed above according to the satellite's position and the Antenna'sgeographic location, by using a compass. These measurements can beobtained by using known tables and known parameters.

[0024] 2. operating the automatic searching components which may beconfigured to search for the symmetry in the three planes mentionedabove. This procedure can be repeated a number of times until attainmentof an acceptable value.

[0025] 3. the system may then be configured to “inform” the user whetheror not the search was done successfully.

[0026] Typically in satellite-based VSAT communications networks, acentral data processing center may communicate with hundreds, thousands,tens of thousand, or even hundreds or thousands of remote sites. At eachof these remote sites, an Antenna (among other things) needs to beinstalled. Under currently available technology skilled technicians arerequired to attend each remote sites to position an Antenna,representing significant costs. The systems and methods described hereineliminate this requirement.

[0027] These and other features of the invention will be apparent uponconsideration of the following detailed description of preferredembodiments. Although the invention has been defined using the appendedclaims, the invention may include one or more aspects of the embodimentsdescribed herein including the elements and steps described in anycombination or sub combination. For example, it is intended that each ofthe above aspects of the invention may be used individually and/or incombination with one or more other aspects of the invention definedabove, in the drawings, and/or in connection with the detaileddescription below. Accordingly, there are any number of alternativecombinations for defining the invention, which incorporate one or moreelements from the specification, including the description, claims,aspects of the invention, and/or drawings, in various combinations orsub combinations. Accordingly, it will be apparent to those skilled insatellite communication art in view of the present specification, thatalternate combinations and sub combinations of one or more aspects ofthe present invention, either alone or in combination with one or moreelements and/or steps defined herein, may constitute alternate aspectsof the invention. It is intended that the written description of theinvention contained herein cover all such modifications and alterations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The foregoing summary of the invention, as well as the followingdetailed description of preferred embodiments, is better understood whenread in conjunction with the accompanying drawings, which are includedby the way of example, and not by way of limitation with regard to theclaimed invention in the accompanying figure in which like referencenumerals indicate similar elements.

[0029]FIG. 1 shows an exemplary block diagram of a system embodyingaspects of the present invention.

[0030]FIG. 2 shows a top level state diagram of a method which may beimplemented using the system shown in FIG. 1.

[0031]FIG. 3 shows one exemplary search algorithm flowchart.

[0032]FIG. 4 shows one exemplary coarse search algorithm.

[0033]FIG. 5 shows one exemplary fine search algorithm.

[0034] FIGS. 6-9 show one exemplary fine search algorithm.

[0035] FIGS. 10-12 show a second exemplary fine search algorithm.

[0036]FIG. 13 shows an example of repeating steps 1 and 2 for theelevation axis.

[0037]FIG. 14 shows that the whole polarization process may be repeateduntil convergence.

[0038]FIG. 15 shows a top level system chart of one exemplary feedbackloop for use in the systems and methods described herein.

[0039]FIG. 16 shows exemplary commands which may be used to operate thesystems and methods described herein.

[0040]FIG. 17 shows time estimations which may result from the use ofsystems and methods described herein.

[0041]FIG. 18 shows systems and methods for optimizing the systems andmethods described herein.

[0042]FIG. 19 shows an exemplary system configuration for the indoorunit described, for example, in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0043] Referring to FIG. 1, embodiments of one or more aspects of thepresent invention may include an automatic satellite positioning system1 having a dish 2, a feed horn 3 receiving signals reflected from thedish 2, a polarization motor 4 for controlling the polarization positionof the feed horn 3, a low noise block 5, coupling a signal from the dish2 and feed horn 3 to and/or from the indoor unit 10 via cable 12.Similarly, the indoor unit 10 may provide a control for communicatingvia cable 13, which may or may not be different from cable 12.

[0044] In still further aspects of the invention, the dish 2 may besupported by a structure which includes, for example, an azimuth (az)motor 6 and/or a elevation (el) motor 9. The control box 7 may beincluded to interface between the indoor unit and the azimuth motor 6,the elevation motor 9, and polarization motor 4. For example, in FIG. 1,a line 8 represents a power voltage and a communication line connectingthe control box to the indoor unit. The D.C. can be separate or can beincorporated within the co-axial cable, i.e. it can be the same wire.

[0045]FIG. 2 shows a top level state diagram 100 describing aspects ofthe system and method for tuning an antenna array. In this embodiment, asearch is performed of the azimuth, elevation, and polarizationpositions. As indicated, the search may be performed in any suitableorder and using a suitable search routine. In the illustratedembodiment, in step 101, the initial positioning level is determined forskew and a rough angle for azimuth and elevation. The polarization maybe set to 0. In step 102, a check may be made to ensure that the controlcable connector is connected to the control box. In step 103, the onbutton is pushed, and a search begins at step 104. Step 104 performs asearch of the azimuth, elevation, and polarization. For each search, theappropriate motor is moved and the search is conducted as describedbelow.

[0046] In step 109, if the detection fails, the fail LED is illuminatedand an error is returned to the user 110. Additionally, an emergencystop 111, 113 may occur where the start/stop button is pressed again112.

[0047] Upon successful detection step 105, the LED or other displayindicating successful detection is illuminated. The motor may be poweredoff so that a manual locking mechanism on the antenna may be engagedpreventing misalignment.

[0048]FIG. 3 shows a first exemplary search algorithm flow chart 200having a course search step, and a fine search step. For determiningazimuth, elevation, and polarization, a first course search may be made203 scanning across until the course search succeeds 204. Where thecourse search succeeds, a fine search (typically symmetrical) isexecuted step 205. The fine search continues until it succeeds 207 orfails 208.

[0049]FIG. 4 shows the steps which may be employed in the coarse search300. The coarse search may move the azimuth or elevation a predeterminednumber of coarse degrees (e.g., 1 degree) and then measure the signal.For example, in step 302 a signal threshold is detected. Where thesignal is greater than a threshold 302, the azimuth, elevation andpolarization is set in step 304.

[0050] Where the signal is not greater than a threshold, the azimuth,for example, is modified. This may continue until the azimuth is out ofrange step 303. Where the azimuth becomes out of range, the elevation ismoved a predetermined amount such as 1 degree step 306. Where theazimuth is within a predetermined range, it is modified by apredetermined amount such as one degree step 301.

[0051] Where the elevation is modified in step 306, a check is performedin step 307 to determine if the elevation is out of range. If theelevation is out of range and no signal was found during the coursesearch, the polarity angle may be turned 90 degrees step 309 and thesearch repeated step 311 at step 301. Where the polarity has beenmodified already, a failure may be indicated in step 310.

[0052]FIG. 5 shows the steps which may be employed in the fine searchfor the azimuth, elevation, and polarization steps 400. In step 401, theazimuth is moved in some direction. If the gradient is negative, thedirection may be switched step 402. The velocity of the motor in movingthe dish may have a fine and course adjustment, with the fine adjustmentmoving the dish more slowly. This process may continue step 403 untilthe system acquires the local maximum azimuth. These adjustments may bedescribed as the phase I-phase III adjustments and shown in FIGS. 6-9.For example, FIG. 6 shows that the local maximum azimuth may be acquiredby starting at a point. The azimuth is scanned in some direction asshown in FIG. 7. Where the gradient is negative, the azimuth is scannedin a different direction, FIG. 8. This process is continued until thegradient is negative again. A threshold may then calculated, FIG. 9, fora symmetrical search. The movement may be stopped when the feedbacksignal is just above a predefined level in order not to lose satelliteacquisition.

[0053] Again referring to FIG. 5, in steps 406, the steps may becontinuous or in small steps of a predetermined amount, e.g., 0.1degrees. Where the search has succeed, step 407, the system may be movedto the maximum azimuth found step 409. Where the search failed, afailure may be indicated, step 408. In step 410, 411, it may bedesirable to continue to move the dish until the signal reading equals amaximum factor. For example, as shown in FIGS. 10-12, the center of theazimuth reading may be located using a symmetrical scan. In oneexemplary embodiment, the center of the azimuth is found by scanning theazimuth axis at a fixed elevation until a negative gradient and feedbacksignal is below a predefined threshold. While scanning, it may bedesirable to capture points which have predefined thresholds such as 2db, 3 db, etc. The step may be repeated in both directions to compensatefor delays. The center may then be calculated using the thresholds asshown in FIG. 12. The dish may then be moved to the center of theazimuth.

[0054] Again referring to FIG. 5, in step 413-415, the above phase 1 andphase 2 steps may be repeated for the elevation axis in phase 3. This isshown as in FIG. 13.

[0055] The steps described in FIG. 5 are continued until the wholeprocess meets a predefined set of convergence criteria which indicatesthe antenna is aligned. This is shown graphically in FIG. 14 where boththe azimuth and elevation are aligned in the polarization process.

[0056]FIG. 15 shows a top level system diagram of the search algorithmwhich may be resident in the indoor and/or outdoor unit. In the mostpreferred embodiments, it is located in the indoor unit and uses themicroprocessor located in the indoor unit. The motor and feedbackprocessing are illustrated in FIG. 15.

[0057]FIG. 16 illustrates commands which may pass between the indoorunit and the motor and/or control unit(s). The commands shown in FIG. 16are by way of example and not limitation.

[0058]FIG. 17 shows the set-up time estimations using aspects of thepresent invention.

[0059]FIG. 18 shows various modifications to the above search toincrease the speed of the search routine.

[0060]FIG. 19 shows an exemplary configuration of an indoor unit. Aswill be known to those skilled in the art, many alternativeconfigurations of the indoor unit may be utilized. The indoor unit maybe one way or bidirectional for two-way communications.

[0061] Having described several embodiments of the automatic antennaesystem in accordance with the present invention, it is believed thatother modifications, variations and changes will be suggested to thoseskilled in the art in view of the description set forth above. It istherefore to be understood that all such variations, modifications andchanges are believed to fall within the scope of the invention asdefined in the appended claims.

We claim:
 1. A method of automatically positioning an antenna on threemutually exclusive orthogonal planes, comprising the steps of:determining initial azimuth, elevation, and polarization positions ofsaid antennae; determining an initial positioning level for skew and arough azimuth angle and elevation; setting a polarization value to 0;and performing a search of azimuth, elevation, and polarization of asatellite by moving said antennae on said three mutually exclusiveorthogonal planes.
 2. A method as recited in claim 1, comprising thefurther step of checking to ensure that a control cable connector isconnected.
 3. A method as recited in claim 1, comprising the furtherstep of providing a failure indication when said satellite is not found4. A method as recited in claim 3, comprising the further step ofstopping movement of said antennae when said failure indication isprovided.
 5. A method as recited in claim 3, comprising the further stepof repeating said step of determining said initial azimuth, elevation,and polarization positions of said antennae, and repeating said methodwhen said failure indication is provided.
 6. A method as recited inclaim 1, comprising the further step of providing a detection indicationwhen said satellite is found.
 7. A method as recited in claim 6,comprising the further step of stopping movement of said antennae whensaid detection indication is provided.
 8. A method as recited in claim7, comprising the further step of locking said antennae after saidsatellite is found so that said antennae is aligned with said satellite.9. A method as recited in claim 8, comprising the further step ofdisconnecting a control cable connector.
 10. A method as recited inclaim 1, wherein said step of performing a search comprises the furthersteps of: performing a course search; and performing a fine search. 11.A method as recited in claim 10, wherein said course search comprises:scanning to determine azimuth, elevation, and polarization, a firstcourse search.
 12. A method as recited in claim 10, wherein said finesearch is performed after a successful course search.
 13. A method asrecited in claim 10, wherein said coarse search comprises moving saidantennae a predetermined number of coarse degrees and measuring anyreceived signal.
 14. A method as recited in claim 13, wherein saidcoarse search further comprises comparing the received signal to athreshold, and setting said azimuth, elevation and polarization whensaid signal is greater than said threshold.
 15. A method as recited inclaim 14, wherein when the signal is not greater than said threshold,said azimuth is changed.
 16. A method as recited in claim 15, whereinwhen said azimuth is out of range, said elevation is moved apredetermined amount.
 17. A method as recited in claim 16, wherein whensaid elevation is out of range and no the satellite was not found duringthe course search, said polarization is turned 90 degrees, and saidcoarse search is repeated.
 18. A method as recited in claim 17, whereinwhen said polarization has previously been modified, a failureindication is provided.
 19. A method as recited in claim 14, whereinwhen the signal is not greater than said threshold, said elevation ischanged.
 20. A method as recited in claim 19, wherein when saidelevation is out of range, said azimuth is moved a predetermined amount.21. A method as recited in claim 20, wherein when said azimuth is out ofrange and no the satellite was not found during the course search, saidpolarization is turned 90 degrees, and said coarse search is repeated.22. A method as recited in claim 12, wherein said fine search comprisesthe steps of: moving said azimuth; and determining if a gradient isnegative and if so switching a direction of movement of said antennae.23. A method as recited in claim 22, wherein said step of moving saidazimuth continues until a local maximum azimuth is acquired.
 24. Amethod as recited in claim 23, wherein said fine search comprises thefurther steps of: calculating a threshold for symmetrical search whensaid gradient is negative a second time; and stopping movement of saidantennae when a feedback signal is just above a predetermined level inorder to maintain satellite acquisition.
 25. A method as recited inclaim 24, wherein said fine search comprises the further step of findinga center of said azimuth readings using a symmetrical scan.
 26. A methodas recited in claim 25, wherein said step of finding the center of saidazimuth readings comprises: scanning an azimuth axis at a fixedelevation until a negative gradient is found and a feedback signal isless than a predetermined threshold; capturing points of pre-calculatedthresholds; repeating said scanning and capturing steps in oppositedirections to compensate for delays; and calculating the center usingsaid thresholds.
 27. A method as recited in claim 24, wherein said finesearch comprises the further step of finding a center of said elevationreadings using a symmetrical scan.
 28. A method as recited in claim 27,wherein said step of finding the center of said elevation readingscomprises: scanning an elevation axis at a fixed azimuth until anegative gradient is found and a feedback signal is less than apredetermined threshold; capturing points of pre-calculated thresholds;repeating said scanning and capturing steps in opposite directions tocompensate for delays; and calculating the center using said thresholds.29. A method as recited in claim 26, wherein said fine search comprisesthe further step of finding a center of said elevation readings using asymmetrical scan.
 30. A method as recited in claim 29, wherein said stepof finding the center of said elevation readings comprises: scanning anelevation axis at a fixed azimuth until a negative gradient is found anda feedback signal is less than a predetermined threshold; capturingpoints of pre-calculated thresholds; repeating said scanning andcapturing steps in opposite directions to compensate for delays; andcalculating the center using said thresholds.
 31. A method as recited inclaim 30, wherein said fine coarse search is continued until apredetermined set of convergence criteria are met indicating that saidantennae is aligned.
 32. A system for automatically positioning anantenna on three mutually exclusive orthogonal planes, comprising: amotor for moving said antennae in around an azimuth axis, an elevationaxis and a polarization axis; and a microprocessor for controllingmovement of said motor and receiving feedback relating to receivedsignals, said microprocessor using a control algorithm to controlpositioning of said antennae to align said antennae with a satellite.33. A system for automatically positioning an antenna on three mutuallyexclusive orthogonal planes, comprising: an indoor unit including asatellite receiver, a telemetric transmission, a drive motor and anelectronic search device; and an outdoor unit including a supervisoryunit, a motor, and a control unit, wherein said outdoor unit searches inthe three orthogonal planes to position the antenna is accordance withmessages received from said telemetric transmission from said indoorunit.